FIG. 1 shows a prior art non-roaming network architecture in which communication for a mobile terminal, or user entity, UE, may be carried through various 3GPP access and network technologies. There is shown a GERAN (GSM EDGE Radio Access Network,˜referred to as 2G) access interface (comprising a BSS (Base Station Subsystem not shown)), a UTRAN (UMTS Terrestrial Access Network,˜referred to as 3G) interface (comprising a NodeB base station (not shown)) and an E-UTRAN (referred to as LTE (Long Term Evolution)) interface (comprising an eNodeB base station (not shown)).
On the core network side, the GERAN and the UTRAN access networks both have interfaces to a SGSN (Serving GPRS Support Node). The MME (Mobility Management Entity) is the key control node for the LTE access-network. It is responsible for idle mode UE (User Equipment) tracking and paging procedures including retransmissions. The MME is involved in the bearer activation/deactivation process and is also responsible for choosing the SGW (Serving Gateway) for a UE at the initial attach and at time of intra-LTE handover involving Core Network (CN) node relocation.
Other known nodes shown in FIG. 1—corresponding to TS23.401 V.10.2.1-2011-01—FIG. 4.2.1-1—are HSS (Home Subscriber Server), PCEF/PGW (Packet Data network (PDN) Gateway) and PCRF (Policy Charging and Rules Function), the later nodes having connection to an operator's IP services, IMS (IP Multimedia Subsystem), PSS (Packet Switch Streaming), etc.
Control plane signaling concerning the user entity is transmitted over the S1-MME interface while user plane signaling concerning the user entity is transmitted over the S1-U user plane. Moreover, there are provided known interfaces S3, S10, S11, S4, S6a, S12, S5, Gx, SGi and Rx.
For a user entity having LTE access capabilities at least the following options noted in table 1 exist:
TABLE 1attachmentstatePS/CS/paging optionsnon-attached——attachedECM-IDLEno PS/no CS,page possibleattachedECM-PS; CS; combined CSCONNECTEDand PS
When a user entity in ECM-IDLE mode needs network service, such as packet switched (PS), circuit switched (CS) or combined CS and PS network service, the Service Request procedure is used according to 3GPP TS 23.410 V10.2.1 (2011-01)-5.3.4.1 and 3GPP TS 24.301 V10.1.0 (2010-12). This procedure is initiated by the user entity, as shown in FIG. 2—corresponding to T823 401 V10.2.1 FIG. 5.3.4.1-1: UE triggered service request procedure. Alternatively, a service request can be requested by the network with a paging message, as shown in FIG. 3—corresponding to TS23.401 V10.2.1 FIG. 5.3.4.3-1: Network triggered service request procedure.
The user entity can request service by transmitting either a Service Request signal or an Extended Service Request signal. The former is used for normal service requests and the latter is mainly used for service requests related to CSFB (Circuit Switched Fall Back).
Therefore, it is provided that a low priority indication may be included in an extended service request NAS (Non-Access Stratum) message, for among others, devices which may have a lower priority. Thereby, the network can chose to discard or reject service requests from user entities which may not need a speedy handling of service. Change requests (CR) to 24.301: “3GPP TSG-CT WG1 Meeting #70, C1-111521, Salt Lake City, Utah (USA). 21-25 Feb. 2011”, describes a low priority as an actual information element to the extended service request, and “C1-111521 3GPP TSG-CT WG1 Meeting #69, C1-110095 Ljubljana (Slovenia). 24-28 Jan. 2011” describes an enhancement to the Extended Service Request so it can be used for other services than CSFB (Circuit Switched Fall Back), i.e. PS services.
The implication of the above options is that the network may check for a low priority indicator when receiving a NAS message from the user entity. If a low priority indicator is set, this may be taken into account by the network to decide on further handling of the message.
As mentioned above, if a user entity needs to change state from IDLE to be serviced by the network it shall initiate a service request procedure. The initial message sent to the network may be selected based on the priority of the request. If a user entity request, e.g. by configuration, is associated with a low priority class, the user entity may send an Extended Service Request NAS message with a low priority indicator being set. If the MME receives an Extended Service Request NAS message with a low priority indicator, the request can be treated with lower priority than NAS messages without a low priority indicator in a network overload or congestion situation.
In the future, Machine-to-machine (M2M) devices are expected to outnumber usual handheld devices. These M2M devices are expected to mainly demand a low quality of service (QoS) class or other forms of a low priority. In particular, many M2M devices will not need a low latency. The expected high numbers of such devices may lead to congestion in the network. Therefore, among others, such devices could make use of the extended service request with the low priority indicator being set.